Stairways employed in buildings and other structures present difficulties to non-ambulatory individuals. For example, a non-ambulatory individual confined to a personal vehicle such as a wheelchair cannot easily negotiate common stairwells. To accommodate such individuals, separate elevator lifts, moving chair arrangements, or ramps are often provided. In stair structures extending a vertical distance that is less than a building story, such as those typically used near the entrance to a building, a separate elevator lift is not always practical, particularly in outdoor environments. In such cases, separate ramps or moving chair arrangements may be provided which facilitate vertical travel by a personal vehicle.
One drawback to the use of a separate ramp to provide personal vehicle access to elevated surfaces is that suitable ramps consume relatively large amounts of space. As a result, existing buildings must often be substantially altered to accommodate the installation of a ramp. In many circumstances, space constraints surrounding the building make installation of a ramp impossible.
Moving chair arrangements offer a solution in such low rise environments. Moving chair arrangements comprise a chair that slides diagonally up and down the stairway. Such arrangements require that the personal vehicle be separately transported up or down the stairway. Because personal vehicles can be quite heavy, separate transport of the personal vehicle can be difficult. Moreover, the movable chair itself, when not in use, nevertheless occupies stairway space and dictates the appearance of the staircase.
Separate vertical wheelchair lifts have also been employed for such low rise environments for use in situations in which there is inadequate room for an access ramp. Such devices, however, while consuming less space than a ramp, nevertheless consume valuable access space and dictate certain architectural parameters. Moreover, separate wheelchair lifts may be impossible to implement in hallways or other narrow environments.
In an attempt to address some of the concerns of the separate vertical lift, lifts have been developed that cooperate with a staircase to provide a lift that fits within a hallway or narrow environment. For example, U.S. Pat. No. 4,457,402 to Del Vecchio et al. shows a lift that is disposed directly in front of a low rise staircase that extends from a lower surface to an upper surface. The lift provides vertical transport of wheelchairs from the lower surface to the level of the upper surface. When the lift rises, the stairs collapse upward to form a bridge platform that allows travel from the lift platform over the area normally occupied by the staircase to the destination upper surface.
Another proposed design of a lift that may be located in a narrow environment is found in U.S. Pat. No. 5,234,078 to Smith. In the Smith patent, a lift platform is located on the upper surface directly behind the ascending stairs. In other words, the lift platform forms a portion of the upper surface. The lift platform provides transport between the upper surface and the lower surface through vertical movement. When the lift platform lowers to the level of the lower surface, the stairs collapse so that they too are substantially on the level of the lower surface. When the lift platforms rises to the level of the upper surface, the stairs reconfigure into a staircase.
A drawback of the designs found in the Del Vecchio et al. and Smith patents discussed above is that they require space equivalent to the area of the lift platform either completely in front of or completely behind the staircase. In some cases, such area is not available. Moreover, because the lift platform is located completely outside the footprint of the staircase, the lift platform creates a potentially displeasing architectural discontinuity with the surface at which it normally rests while not in operation. For example, as shown in FIG. 1 of the Smith patent, the lift structure requires special wall and floor structures that create visible discontinuities along the floor and wall. Likewise, the lift shown in FIG. 1 of the Del Vecchio et al. patent undesirable creates a plainly visible discontinuity along the intersection of the platform and lower (ground) surface. Such discontinuities significantly affect the appearance of an architectural structure.
There exists a need, therefore, for a lift structure for providing access to personal vehicles between a lower surface and an upper surface that has reduced impact on the architectural and/or design aspects of a structure, and may be employed in structures with space constraints.